In New York City, police give credit to the social media site for helping them arrest and indict 49 gang members whose shootings terrorized the streets of Brooklyn. These jailed gang members are from two rival gangs, the Rockstarz and the Very Crispy Gangsters, who reportedly moved their street fights online.

Here’s how it worked: First, police say, they added their foes as Facebook friends. Then they littered their rivals’ walls with jeers and threats. Some even posted photographs they’d taken standing in front of their enemies’ homes on Facebook, according to the New York Times, as well as bragging about episodes of murder and retaliation. Bad move.

“Because of these individuals’ insatiable desire to brag about what they did, these investigators were able to draw a virtual map of their activities and bring them to justice,” said New York City Police Commissioner Raymond W. Kelly.

According to police, one man posted a photo of himself taking the watch and belt of a wounded gang member he had just gunned down. “I can’t give it back,” the caption says. “You can’t walk no more.”

The escalation began after a member of Rockstarz killed one of the Very Crispy Gangsters in 2009, police say. Over the next three years 10 shootings occurred, causing the deaths of three gang members and the injury of one 10-year-old boy, who was hit by a stray bullet while watching cartoons in his apartment.

The majority of these gang members are in their early 20s; the oldest is 23 and youngest under 18. They have been charged with murder, attempted murder and conspiracy.